Q. WHEN THE SPEED OF A MONORAIL IS 60KM/HR IT REACHES ON TIME . IF THE SPEED IS INCREASED BY 20 KMS IT REACHES ONE HOUR REALIER THEN HOW MUCH DISTANCE DOES THE MONORAIL COVER?

Option
A) 240KMS
B) 250KMS
C) 260KMS
D) 270KMS

• let distance=d
  1st case time t=d/60 hr
  2nd case time t= (d/80)-1 hr
  by equating both d=240 km
• 11 years agoHelpfull: Yes(3) No(1)
• 240 kms
  WHEN THE SPEED OF A MONORAIL IS 60KM/HR IT takes 4 hours.
  WHEN THE SPEED OF A MONORAIL IS 60+20=80KM/HR IT takes 3 hours i.e. 1 hour less.
  
  
• 11 years agoHelpfull: Yes(1) No(1)
• Ans.A) 240 km
  Speed=Distance(d)/Time(t),
  i) when the speed is 60km/hr, d= 60t
  ii) when the speed is increased by 20 km i.e 80km/hr, t reduces by 1 hr,
  80=d/t-1
  80t - 80=d
  On solving equation (i) & (ii),
  60t= 80t-80
  20t=80
  t=4 hrs
  Putting value of t in eq. (i), we get d= 60* 4 i.e 240.
  
• 11 years agoHelpfull: Yes(1) No(0)
• travelling 60km/hr it travels a distance d in time t. then time increase 1 unit and speed is 80km/hr 80=d/(d+60/60) which becomes 8d+480=6d solving. we get d=240
  ANS:A)240kms
  note:negative signs are neglected in speed distance calculations
• 11 years agoHelpfull: Yes(1) No(1)